1. Field of the Invention
The present invention relates to a collision avoidance system, program, and method of a mobile unit for avoiding collision with an obstacle, and more particularly, to a collision avoidance system, program, and method of a mobile unit which estimates a collision probability and an approaching direction of an obstacle using a plurality of motion detectors which are modeled on the optic lobe neurons of flies.
2. Description of the Related Art
Collision avoidance against an obstacle is a function necessary for a mobile unit to arrive at a destination safely. Many techniques for avoiding collision with an obstacle have been proposed, which are based on optical flows extracted from visual information such as camera image.
For example, Japanese Patent Application Publication No. 11-134504 discloses a device which detects collision with an obstacle based on a value obtained by subtracting a vector sum of optical flows in a direction converging to a given point from a vector sum of optical flows in a direction diverging from the same point. A neural network is used for calculating the difference between the vector sum in diverging direction and the vector sum in converging direction.
In addition, Japanese Patent Application Publication No. 2003-51016 discloses a system in which vector sums of optical flows in two different areas in an image are calculated respectively using spatial filters such as Gaussian filters, and an approaching obstacle is detected based on the difference between these vector sums.
With respect to avoidance behavior of a living body responsive to visual information, a living body performs wide variety of rapid and proper avoidance behaviors responsive to complex external environments in the real world. Also in a collision avoidance technique of a mobile unit, it is desirable that optimal behavior is selected according to the direction in which an obstacle is approaching the mobile unit or the like. However, a technique for detecting a direction in which an obstacle is approaching has not been presented by conventional techniques such as in the above documents.
The present invention provides a collision avoidance technique for a mobile unit which allows avoidance of collision with an obstacle by detecting a direction in which the obstacle approaches the mobile unit based on visual information. A behavior is selected according to the approaching direction of the obstacle.